The republic of letters is in thrall to an unprecedented scientism. The word is out that human consciousness - from the most elementary tingle of sensation to the most sophisticated sense of self - is identical with neural activity in the human brain and that this extraordinary metaphysical discovery is underpinned by the latest findings in neuroscience. Given that the brain is an evolved organ, and, as the evolutionary biologist Theodosius Dobzhansky said, nothing in biology makes sense except in the light of evolution, the neural explanation of human consciousness demands a Darwinian interpretation of our behaviour. The differences between human life in the library or the operating theatre and animal life in the jungle or the savannah are more apparent than real: at the most, matters of degree rather than kind.

These beliefs are based on elementary errors. Just because neural activity is a necessary condition of consciousness, it does not follow that it is a sufficient condition of consciousness, still less that it is identical with it. And Darwinising human life confuses the organism Homo sapiens with the human person, biological roots with cultural leaves. Nevertheless, the coupling of neuromania and Darwinitis has given birth to emerging disciplines based on neuro-evolutionary approaches to human psychology, economics, social science, literary criticism, aesthetics, theology and the law.

These pseudo-disciplines are flourishing in academe and are covered extensively in the popular press, in articles usually accompanied by a brain scan (described by the writer Matt Crawford as a "fast-acting solvent of critical faculties"). Only last month, David Brooks asserted in the New Yorker that "brain science helps fill the hole left by the atrophy of theology and philosophy".

There are more cautious writers, but even for them the attraction of biologism seems irre­sistible. V S Ramachandran asserts correctly, in his new book, The Tell-Tale Brain: Unlocking the Mystery of Human Nature, that humanity "transcends apehood to the same degree by which life transcends mundane chemistry and physics". Even so, he is prepared to claim that we enjoy Picasso's paintings for the same reason that gull chicks prefer fake maternal beaks with an excess of markings to the real thing: they are "superstimuli". Both books under review acknowledge the uniqueness of human beings but relapse repeatedly into accounts of the mind, self and consciousness that appeal to a mixture of neuroscience and evolutionary theory. Despite the ingenuity and erudition of the authors, they serve only to illustrate the shortcomings of neuroscientific attempts to capture human consciousness and human nature.

The theoretical psychologist Nicholas Hum­phrey's Soul Dust: the Magic of Consciousness is extremely ambitious. He claims to have solved "the hard problem" of consciousness: how it is that a piece of matter such as a human organism (or its brain) can have conscious experiences, items that do not seem of a nature that can be conjured out of matter alone. His "explanation" is confused and confusing, not the least for his conclusion that consciousness is "a magical mystery show that you lay on for yourself", a "self-created entertainment for the mind", staged by one part of the brain to influence another part of the brain. He concedes that he does "not expect everyone to be convinced it is a good idea just yet". You bet. "Laying on a show", rather than offering an explanation, is precisely the kind of thing that has to be explained; indeed, it seems a somewhat late, higher-level or sophisticated mode of consciousness that presupposes, rather than helps us to understand, more basic modes of awareness such as sensation.

The idea of consciousness as a "show" is ultimately derived from the bankrupt representational theory of the mind - a notion that things are present to us by virtue of being "represented" or "modelled" in the brain. You cannot get to representation, however, without prior (conscious, first-order) presentation, so the latter cannot explain the former. Neuroscientists of consciousness try to elude this obvious objection by asserting that representations are not (necessarily) conscious. In fact, all sorts of aspects of consciousness are not conscious after all. According to Humphrey, "before consciousness ever arose, animals were engaged in some kind of inner monitoring of their own responses to sensory stimulation". What is "inner" about unconscious processes, material events in the material brain? And how can they amount to monitoring? These questions are not silenced by the author's reassurance that consciousness is "the product of some kind of illusion chamber, a charade". Nor does Humphrey tell us how he awoke from his consciousness to discover that it is an illusion.

He elaborates his theory of mind with the assistance of opaque concepts such as "sentition" and "ipsundrum". Sentition is "a privatised expressive activity", whereby the sensation of the redness of a tomato, for example, means nothing other than for you to observe your own active "redding". Make of that what you will. As for the ipsundrum, this is the seed of the self, analogous to illusory or impossible objects such as the Penrose triangle, which somehow generates the illusion of a world out there corresponding to a me "in here", though it still has to be "'seen' by an internal observer". It is, we are told, a "mathematical object", "a complex pattern of dynamic activity in neural circuits". This is hardly the kind of thing on which you could hang your hat, much less your biography.

Consciousness is "the set of brain events that occur when the subject observes, from a certain privileged position, his own ipsundrum which is the integral of the activity in a special kind of feedback loop". Observes? Who or what observes? Privileged position? Privileged by virtue of what? How can there be privileged positions in the material world of which the brain is a part? Humphrey describes these ideas as "nice". I beg to differ. I looked in vain for evidence to support them and was not surprised to find none.

Despite my 30 years in clinical neuroscience, I found Antonio Damasio's long and painstaking exposition of his ideas about mind, self and consciousness extremely hard going, though the dust jacket of Self Comes to Mind: Constructing the Conscious Brain carries an impressive cast of lay encomiasts, including Peter Brook, Yo-Yo Ma and V S Naipaul. Damasio's emphasis on the importance of the emotions and the body outside of the brain, an approach that distances him from those for whom the brain-mind is a computer, and consciousness the input-output relations of its software, is something for which one should be grateful, but beyond this there is little in which to rejoice. If there were explanations of how the "self comes to mind" or "constructing the conscious brain" in his book, I missed them. The story he tells seems to be a description of what the brain (or brain-plus-body) must achieve to be the basis of consciousness, rather than how it might achieve this.

Damasio makes life difficult for himself by beginning from some rather surprising assumptions. Mind, he says, is largely unconscious. Even insects have minds, apparently, which makes one question his criteria for mindfulness. At any rate, it is obvious that something else is needed to make minds conscious in the interesting way that your mind, gentle reader, is conscious. We are asked to accept another questionable assumption: that it is selves, with their first-person perspective, that are the magic ingredients. Isn't this topsy-turvy? Surely consciousness is the precondition of the self, rather than the other way round.

Granted, Damasio's selves are rather more substantial than Humphrey's ipsundrum, and they come in different classes - from the lowly protoself, with its primordial feelings, to the action-driven core self and, finally, the auto­biographical self that incorporates spiritual and social dimensions - which, by the way, he also accords to wolves (though we are awaiting the first memoir). But what he has to say about these working class, middle-class and upper-class selves does not explain how they bring consciousness to the mind. His account of how the selves are built up from the "brain's hierarchical nested componentiality" equally does nothing to explain how they might make a piece of matter such as an organism or its brain aware that it exists, and aware, too, of its material surroundings as a world in which it acts out its destiny. Why should the wiring together of bits of the brain - or bits of the brain and bits of the body - turn bodily events into things that are felt, and felt to be one's own, or make brain responses to what is happening in the body amount to an awareness of what is happening in the body? After all, as he points out, the great bulk of so-called brain maps are not associated with any kind of consciousness.

Damasio's uncertainty about the neural basis of consciousness betrays him in many ways. He vacillates between ascribing to certain parts of the brain main roles in consciousness and then arguing that it arises out of the brain as a whole. Equally puzzling is his disregard for his own distinction between the unconscious mind and the conscious self. He tells us that there are certain areas of the brain - the cerebral cortex and the brain stem - that are critically important to mind-making (but fails to tell us how they do it). This makes it difficult to understand how insects can be mindful, given that they lack such structures or anything comparable to them. I now suspect he means "mind" in the conventional sense of something that is conscious.

At times, the illusion of explanation becomes quite strong. When, like Humphrey, Damasio ascribes a crucial role in the generation of selfhood to "feedback loops" in the brain, this does convey the sense of consciousness being turned back on itself until it becomes self-conscious or self-like. Yet there is no reason why feedback loops should do this. They are evident throughout the biosphere, even at the level of single cells - and they are present in the meanest pocket calculator. Such loops could deliver a self only if consciousness had already been achieved in the loops that are feeding back on themselves.

The illusion of explanation is also sustained by use of language that straddles the barrier between brain and consciousness. One of Damasio's favourite words is "image", which gets 34 entries in the book's index. Images are the basis of first-person being and hence, according to him, consciousness. Yet at the same time they are for the most part not experienced at all, and unconscious minds, such as those of insects, are seething with them. I suspect he is involuntarily slithering between two uses of the word image: to mean an unconscious material replica, such as a reflection in a mirror, and to denote an element of consciousness, as when I am aware of a mirror image or call something to mind.

Neither Humphrey nor Damasio deals with the hard problem of consciousness - explaining how certain material entities such as ourselves feel what is happening within, to and around us. Even so, they are confident that consciousness must be biological and, therefore, must have arisen because it conferred selective advantage. Given that everything of biological use which is achieved through consciousness could be achieved without it (though once you are dependent on consciousness it's a good idea to stay that way!), it is difficult to put one's finger on what this advantage could be.Humphrey devotes several chapters to discussing the survival value of being aware of the world with which we interact. He concludes that "the simple pleasure of pure being" is enough to drive us to work harder to live, out of a "raw fear of oblivion", and this is how consciousness earns its (metabolically expensive) keep. The idea that life is such fun for conscious creatures, they do not want to let it go, is open to the simple objection that the sum total of experience may not be very pleasant. Thomas Hardy's view that "A time there was . . . Before the birth of consciousness,/When all went well" is not shared by Humphrey.

At a certain level of self-consciousness, one becomes aware of one's mortality. Surely it must be demotivating to realise that, whatever you do, you will be obliterated. No, Humphrey says. We have various strategies for "cheating death": discounting the future in favour of the present; identifying with cultural entities that will survive our death; even denying the finality of bodily death. His paean to the joy of life, which draws on poets, artists and philosophers, is a digression from the central promise of the book - to explain how "brain activity under its neuroscientific explanation amounts to mental activity under its experiential description".

Early in Self Comes to Mind, Damasio asks: "Is it reasonable to devote a book to the question of how brains make conscious minds?" Apparently it is, because:

Understanding the circumstances in which conscious minds emerged in the history of life, and specifically how they developed in human history, allows us to judge perhaps more wisely than before the quality of the knowledge and advice those conscious minds provide.

This is modest compared to the usual hyping of neuroscience. The head of the RSA, Matthew Taylor, has urged that we look to neuroscience to guide social policy and move on from the old ideologies of right and left to the right and the left hemispheres of the brain. The evolutionary biologist David Sloan Wilson has argued that we should "connect the world of evolutionary science with that of public policy formation". Professors Semir Zeki and Oliver Goodenough anticipate a "millennial future, perhaps only decades away" when "a good knowledge of the brain's system of justice and of how the brain reacts to conflicts may provide critical tools in resolving international political and economic conflicts". Untidy decision-making processes in the law courts will be replaced by a "biological justice" that can link actions with the neural activity that drove them as well as the biological bases of that activity.

The conceptual confusions notwithstanding, these two books have greater merits than many contenders in an overcrowded field, though they fail to give a coherent neurological account of even the most basic elements of consciousness. Yet it is premature to appeal to neuroscience and evolutionary theory to advance our understanding of human life or drive social policy. And, pace David Brooks, "the atrophy of philosophy" is something that should concern us, rather than make us celebrate.